"Still, Firefox OS could have a big impact on the Web even if it never gains significant market share. By pushing the Web forward, Mozilla is helping to ensure that mobile websites will continue to be relevant even as developers create hundreds of thousands of proprietary apps. Firefox could lose the battle for the smartphone OS market but still win the war for open standards."

Local storage handling. Try using this site: http://www.filldisk.com on any browser and watch the increasing use of disk space in real time (make sure to not fall asleep otherwise your RAM will be easily filled up and make your system slow). Only Firefox including inside Firefox OS is immune of this hack.
Here is the details how it works: http://feross.org/fill-disk/